(CNN) -- Sen. Barack Obama became the first African-American to lead a major party ticket Wednesday as he secured the Democratic Party's nomination for president at the Democratic National Convention in Denver, Colorado.

iReporter Suzy Coyle said there's "optimism in the air" in Denver.

Obama will accept the nomination Thursday night in front of an estimated 70,000 people at Denver's Invesco Field.

His appearance follows three days of convention speeches from prominent Democratic Party leaders. Sen. Joe Biden, Obama's running mate, and former President Bill Clinton were among Wednesday's featured speakers.

Clinton remarked on the significance of Obama's nomination, describing it as a "historic chance."

In anticipation of Obama's address, iReporters across the country are reflecting on the momentous milestone.

"I frankly never thought I'd live to see this day," said John W. Mack, former president of the Los Angeles Urban League.

Mack, who was a student leader in Atlanta, Georgia, during the civil rights movement, said that Obama's nomination "creates the possibility ... of ultimately fulfilling Dr. King's dream."

Thursday's speech coincides with the 45th anniversary of Martin Luther King's famous "I have a dream" speech.

Referencing King's speech, Mack explained that the historic moment is especially poignant for "Americans who worked so hard to reach the point that an individual be truly judged based on the content of his character, not the color of his skin." iReport.com: See what Mack has to say

Mack's commentary on iReport.com spurred a passionate discussion between commenters. Among the users, Annette Chandler shared her thoughts on Obama's nomination.

"As a Caucasian female living in New York, I never thought I'd see this day either," she wrote. "I am thrilled beyond belief that so many see (and support) the content of Obama's character. It is proof that we are finally putting the issue of color where it belongs -- behind us."

Suzy Coyle traveled to Denver from Topanga Canyon, California, for the convention.

"I am not a delegate, just an Obama supporter. I'm here to witness and be a part of history," she said.

"It is so exciting to be here in Denver," Coyle wrote on iReport.com. "There is optimism in the air. There is hope and celebration in everyone's eyes."

Coyle, a professional photographer, has spent her time in Denver chronicling the sights of the convention. In her photos, the capital city is covered in signs, posters and T-shirts emblazoned with the word "change," a major theme throughout Obama's presidential campaign.